This invention relates generally to improvements in water purification systems of the type adapted to provide a supply of purified water for drinking, cooking, etc. More particularly, this invention relates to an improved reverse osmosis unit for use in water purification systems, wherein the reverse osmosis unit includes a control valve for regulating water inflow to the system.
Water purification systems in general are relatively well-known in the art for use in producing a supply of purified water from ordinary tap water or the like. Such water purification systems commonly include a reverse osmosis unit having an inlet connected to a feed or tap water supply. The feed water supply flows through a reverse osmosis membrane which separates the inflow into two water outflows, namely, a relatively pure water supply and a relatively impure waste or reject water supply having impurities concentrated therein. The produced purified water is normally coupled for flow into a suitable storage vessel awaiting dispensing, for example, through a faucet valve or the like, whereas the reject or waste water flow is normally discharged to an appropriate drain for disposal. Within the storage vessel, the produced pure water is normally maintained within a chamber defined in part by a resilient bladder or diaphragm. Some systems utilize a charge of compressed air or the like acting against the bladder to expel the pure water through an open faucet valve, as depicted, for example, in U.S. Pat. No. 3,568,843. Other systems rely upon the reject water flow to provide a driving force acting upon the bladder to expel pure water when a faucet valve is opened. See, for example, U.S. Pat. Nos. 4,585,554; 4,595,497; and 4,743,366. In either system type, the reverse osmosis membrane is commonly provided in the form of a disposable cartridge adapted for easy replacement on a periodic basis due to particulate and/or residue accumulation, typically at intervals of about one to three years in a residential water supply environment.
In such reverse osmosis water purification systems, the production of purified water is relatively slow in comparison with typical tap water flow rates through a faucet valve. More specifically, for proper operation of the reverse osmosis membrane, a fluid backpressure must be maintained by appropriate restriction of a reject water outlet to insure migration of a portion of the feed water inflow through the membrane for purification purposes. This operation unfortunately results in slow pure water production at normal water supply pressures, whereby the storage vessel is essential to collect and store a quantity of pure water sufficient to meet normal demand surges. However, when the storage vessel reaches a substantially filled condition, further production of purified water by the reverse osmosis unit is diverted through a relief means to a drain resulting in substantial water waste. Such water waste undesirably increases the overall operating cost of a water purification system, and can be especially undesirable in geographical regions having limited water supplies.
A variety of valve mechanisms have been proposed in the prior art for throttling or halting feed water inflow to a water purification system whenever a pure water storage vessel or reservoir reaches a substantially filled condition. Such valve mechanisms, however, have generally comprised relatively complicated structures provided as separate system components and including a variety of movable valve structures and related seal members, etc. While some of these valve mechanisms have satisfactorily reduced water waste in water purification systems, the complex structure and operation of such devices have undesirably increased system costs and provided mechanical components subject to periodic failure and replacement. Accordingly, to insure proper system operation, it has been necessary to service such valve mechanisms on a periodic basis for maintenance or repair purposes.
There exists, therefore, a significant need for further improvements in water purification systems, particularly with respect to simplification of water inflow control valves designed to throttle or halt feed water inflow when a purified water reservoir reaches a filled condition. Moreover, there exists a need for such inflow control valves designed to operate substantially without risk of valve component failure. The present invention fulfills these needs and provides further related advantages.